Rolled strips produced from metal ingots heated in such a furnace are of different quality at their beginning and their end, as compared with the rest of the strip. Such differences in quality are unwanted especially with transformer laminations. Investigations have shown that peak temperatures in the area of the ends of the ingots are responsible for these differences quality. The peak temperatures at the ends of the ingots can be 20.degree. to 30.degree.C. higher, than the temperature of the remaining part of the ingot. This variation in heating is a consequence of the ingot being heated from five sides in the area of the ends, whereas in the middle part it is heated from four sides, only. With continuous heating furnaces operated at temperatures exceeding 800.degree. C., heating is effected approximately 80% by radiant heat.